alk what is a good number

[sisie5]

just tested my pool today after shocking last night he are my numbers.what is a good reading for alk.I have been dealing wiht algea.Need to add more bleach to bring to shock 15 ppm.also need to vacuum again,question should I wait to vacuum until I get better readings.Im new to all this.Thanks

thanks

FC-8.5
CC-0
TC-8.5
pH-7.8
ALK-170

[GraceByDesign]

Generally a TA of 80-125 is suggested here.
Vacuuming does not affect anything except the amount of debris, so is independent of your numbers. Vacuum when you get junk in the pool. The longer you let the junk sit, the higher the risk of CC's as the junk starts to break down.

[aylad]

Don't know what kind of pool you have--if it's vinyl lined, then alk is a little high at 170, but it really doesn't have much effect on the pool--I'd leave it alone 'til you get your algae issue taken care of. You don't mention a CYA level in your pool, and the level you need to take your chlorine to inorder to kill the algae depends on your CYA level. Either way, 8.5 isn't high enough to do you any good.

While you're shocking, you can go ahead and vaccuum, but you also need to be brushing daily and have your filter running 24/7 to help rid the pool of the algae once it dies.

Janet

[sisie5]

MY cya is 40.just did put another 2 gal of bleach in again.pool still have algea
im just about ready to drain and close the pool.Im so tired of vacuumming

[mas985]

It would help your chlorine to work a bit better to drop the PH down to 7.4 or even 7.2. This will be harder to do with the higher alk as it will resist lowering the pH but might be worth it.

[chem geek]

Mark is correct about lower pH being more effective for chlorine, but in the presence of CYA the influence on chlorine effectiveness vs. pH is significantly reduced. These graphs (http://www.poolforum.com/pf2/showpost.php?p=32912&postcount=8) show how a change from a pH of 7.8 to a pH of 7.2 improves chlorine effectiveness by less than 30% so increasing FC by 30% would do the same thing. If there were no CYA present, then the same 7.8 to 7.2 pH change would improve chlorine's effectiveness by over 110% (more than double).

Richard